A Bridgeport, CT chiropractor became the sixth health care provider to admit his involvement in a multi-million dollar insurance fraud in which medical treatment for auto accident victims was exaggerated to obtain bigger lawsuit settlements.

George U. DeCarvalho, 56, owner of DeCarvalho Spine and Rehab, 3715 Main St., pleaded guilty to conspiring to commit health-care fraud during proceedings before U.S. District Stefan R. Underhill. DeCarvalho, who is represented by Andrew Bowman, was released on a promise to appear in court for his Sept. 21 sentencing. He faces anywhere from six to 16 months in prison at that time.

The chiropractor is the fourth of that profession to plead guilty in a case the FBI dubbed Operation Running Man. FBI Special Agent Daniel Curtin is heading the probe.

Jennifer Lynne, Jennifer Netter and Marc Kirshner are the other local chiropractors who admitted their involvement. Additionally, Dr. James W. Marshall, who operates Immediate Medical Care in Monroe, and Francisco Carbone, a former doctor and psychiatrist, also pleaded guilty to charges.

The investigation has targeted health-care providers and an elderly lawyer who specializes in personal injury cases.

Assistant U.S. Attorney Christopher Schmeisser said the scam ran from December 2006 to February 2010. The participants agreed to exaggerate injuries and providers billed for extensive treatment and tests, some of which were not performed. They then split the insurance proceeds.

Documents filed in federal court claim DeCarvalho's take ranged from $30,000 to $70,000.

The probe, which included the use of undercover agents who recorded conversations, focused on the lawyer whose personal injury clients received some form of state aid. Court documents claim the unnamed lawyer would send clients to chiropractors for treatment. Carbone, whose medical license was suspended in 1998 and then revoked in 2005, would write orders for treatment which often included nerve tests that Kirschner's offices in Bridgeport and Stamford would perform. Carbone also would recommend that Marshall write prescriptions for narcotic pain killers for the patients.

DeCarvalho was both a provider and a patient in the scheme, according to court documents.

He shared office space with Carbone and would provide treatment for some of the patients.

But on May 18, 2007, DeCarvalho was involved in an auto accident in which the other driver was found to be at fault.

Carbone fabricated medical records and submitted claims for DeCarvalho which led to the chiropractor receiving a $4,500 injury settlement, according to court documents.